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NEUROPHARMACOLOGY
Department of Pharmacology and Toxicology, Medical Campus, Virginia Commonwealth University, Richmond, Virginia (K.J.J., B.R.M., M.I.D.); and Unité de Recherche Associée Centre National de la Recherche Scientifique Recepteur et Cognition, Institut Pasteur, Paris, France (J.P.C.)
It has been suggested that the negative effects associated with nicotine withdrawal promote continued tobacco use and contribute to the high relapse rate of smoking behaviors. Thus, it is important to understand the receptor-mediated mechanisms underlying nicotine withdrawal to aid in the development of more successful smoking cessation therapies. The effects of nicotine withdrawal are mediated through nicotinic acetylcholine receptors (nAChRs); however, the role of nAChRs in nicotine withdrawal remains unclear. Therefore, we used mecamylamine-precipitated, spontaneous, and conditioned place aversion (CPA) withdrawal models to measure physical and affective signs of nicotine withdrawal in various nAChR knockout (KO) mice. β2,
7, and
5 nAChR KO mice were chronically exposed to nicotine through surgically implanted osmotic minipumps. Our results show a loss of anxiety-related behavior and a loss of aversion in the CPA model in β2 KO mice, whereas
7 and
5 KO mice displayed a loss of nicotine withdrawal-induced hyperalgesia and a reduction in somatic signs, respectively. These results suggest that β2-containing nAChRs are involved in the affective signs of nicotine withdrawal, whereas non-β2-containing nAChRs are more closely associated with physical signs of nicotine withdrawal; thus, the nAChR subtype composition may play an important role in the involvement of specific subtypes in nicotine withdrawal.
Address correspondence to: Dr. M. Imad Damaj, Department of Pharmacology and Toxicology, Virginia Commonwealth University, Box 980613, Richmond, VA 23298-0613. E-mail: mdamaj{at}vcu.edu
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L. L. Merritt, B. R. Martin, C. Walters, A. H. Lichtman, and M. I. Damaj The Endogenous Cannabinoid System Modulates Nicotine Reward and Dependence J. Pharmacol. Exp. Ther., August 1, 2008; 326(2): 483 - 492. [Abstract] [Full Text] [PDF] |
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